魔，梵文 Mara, 魔罗，此云杀者，能杀害众生，法身慧命故。汉语的魔之一字，来自佛经，来自梵文，为魔罗的简称。如下：

魔，汉语常用字（一级字） [1]  ，读作mó，最早见于《说文》小篆，是随着南北朝佛经译文开始产生的 [2]  。本义为梵语魔罗的简称；引申泛指恶魔，怪物；又引申为邪恶的人或势力；妖魔容易引起人们好奇，所以又引申指神奇的、对某事物爱好入迷等 [3]  。

魔有四种，无非都是干扰修行令不入正道的四种因素。但魔由心生，因心外无法。故，干扰起时，唯一心内观即可。

The word Māra comes from the Sanskrit form of the verbal root mṛ. It takes a present indicative form mṛyate and a causative form mārayati (with strengthening of the root vowel from ṛ to ār). Māra is a verbal noun from the causative root and means 'causing death' or 'killing'.^[4] It is related to other words for death from the same root, such as: maraṇa and mṛtyu. The latter is a name for death personified and is sometimes identified with Yama.

The root mṛ is related to the Indo-European verbal root *mer meaning "die, disappear" in the context of "death, murder or destruction". It is "very wide-spread" in Indo-European languages suggesting it to be of great antiquity, according to Mallory and Adams.^[5]